Photovoltaic (PV) cells produce power over a wide voltage range depending on the amount of sunlight and the temperature of the photovoltaic cell. There are National Electric Code and class-of-equipment restrictions that make PV arrays much more cost effective when sized for a maximum of 600 Vdc. In order to source AC power into the electric utility grid, over the expected range of DC voltages, prior art utility-interactive inverters use two power conversion stages.
In all prior art topologies discussed, 100% of the throughput power is processed twice and power is lost in each conversion stage. The invention is an improvement over the prior art because the bulk of the DC-to-AC conversion is done in one direct conversion and only 0% to 25% of the throughput power is processes twice for a worst-case equivalent of 1¼ conversion steps, instead of 2. This translates to at least 38% less complexity, cost and conversion losses over the prior art.